1. Field of the Invention
This invention relates generally to the field of fermentation, and more particularly, but not by way of limitation, to a fermentation apparatus for continuously converting agricultural raw materials into a fermented liquor.
2. Description of the Prior Art
The fermentation of agricultural raw materials to produce ethanol is well known. The production of ethanol from agricultural raw materials, such as corn, wheat, sugar cane, potatoes, beets, Jerusalem artichokes, and the like, has recently become of great importance in the United States as a source of liquid fuel.
In the past foreign crude oil has provided the raw materials for about one-half of the liquid fuels consumed in the United States. However, with the recent instabilities in many of the foreign oil producing countries the cost of the foreign produced crude oil, as well as the uncertainty of the supply of the crude oil, has resulted in the direct efforts to reduce the dependency of the United States on foreign crude oil as the primary source for liquid fuels.
Ethanol is a liquid fuel that can substitute domestic renewable resources for petroleum products now and in the years to come. Fermentation ethanol, a nonpetroleum fuel, is attaining widespread use in the United States in the form of gasohol, a blend of ten percent agriculturally derived anhydrous ethanol and ninety percent unleaded gasoline.
Ethanol can be made by the fermentation process from three types of agricultural raw materials, namely saccharines (materials in which the carbohydrate is present in the form of simple, directly fermentable sugars containing 6 and 12 carbon atoms, such as glucose, fructose, and maltose), starchy materials (materials containing more complex carbohydrates such as starch and inulin that can be broken down into simple sugars containing 6 and 12 carbon atoms by hydrolysis with a weak acid or by the action of enzymes in a process called malting), and cellulose materials (materials containing cellulose that can be hydrolyzed with an acid into fermentable sugars).
The production of ethanol by fermentation techniques has been known for many years. Basically, fermentation is a process in which microorganisms, such as yeast, convert the simple sugars of mash into ethanol and carbon dioxide. The agricultural raw material employed in the fermentation process, as well as the process steps required to convert the carbohydrates, starchy materials, or cellulose materials of the agricultural raw materials into the sample, directly fermentable sugars containing 6 and 12 carbon atoms, (i.e., glucose, fructose, and maltose), can vary widely and will be dependent upon the particular agricultural product employed as the raw material in the fermentation process.
The fermented liquor (i.e., beer) resulting from the fermentation of the fermentable sugars in the mash is generally an aqueous solution containing about ten weight percent ethanol. The fermented liquor is then distilled to obtain the anhydrous ethanol for use as a fluid fuel.
While the fermentation of agricultural products as described above has been known for many years, the fermentation apparatus used in carrying out the fermentation have generally been batched reactors or complicated, expensive continuous reactors. While such reactors, whether batched or continuous fermentation reactors have met with success, a need has now arisen for an improved fermentation apparatus which will enable one to employ flow processing techniques in the production of ethanol from agricultural products which is inexpensive, simple in construction, and efficient in operation. However, such a fermentation apparatus must be capable of economically producing ethanol from the agricultural products using conventional yeast materials.